Opposite rotating propeller drive



Feb. 25, 1947. I w. G. LUQD UIS'T 2,416,662.

OPPOSITE ROTATING PROPE LLER DRIVE Filed ep 2, 1939 x S; ///z an H .wwWm S Wm @M Q WM 3 Q s Q 7 w m Y Mm? \N. MN $1 VMAM H II m INVENTOR WI'I'oN 6. Lwwawsz- ATTORNEY 1947- w. e. LUNDQUIST OPPOSITE ROTATINGPRQPELLER DRIVE Fil ed Sept. 2; 1939 2 Sheets-Sheet '2 INVENTQR WILTON611MHz ATTORNEY Patented F b. 25, 1941 UNITED STATES PATENT OFFICEOPPOSITE ROTATING PROPELLER DRIVE. 3

Wilton G. Lundquist, Hohokus, N. 3., assignor to Wright AeronauticalCorporation, a corporation of New York Application September 2,1939;Serial No. 293,239

' This invention relates to aircraft power plants and is concerned withtandem propellers oppositely driven by a single engine, and withthegearing and control means for the propellers.

An objectof the invention is to provide a novel form of reduction gearhaving driven shafts rotating in opposite directions. A further objectis to'provide a reduction gear having a torque reactionmember capable ofoscillation in response 12 Claims. (Cl. 170-1353) vide a tandempropeller reduction gear in which the speed of the two propellers ismaintained uni-f form, and alternately td provide a gear in which thespeed of the two propellers may differ but in which the torque of eachis the same. Further objects of the invention comprise thdetailed-structure of the embodiment shown inthe drawings in which,

Fig; 1 is a longitudinal section through an engine nose incorporatingthe reduction gear,

Fig. 2 is a fragmentary section of the reduction gear on a differentradius, comprising in general a section on the line 2-2 of Fig. 4,

Fig. 3 is a fragmentary section of part of the gear on the line 3-3 ofFig. 4,

Fig. 4 is a transverse section through a sector of the gear taken ingeneral on the line 4- -4 of Fig. 1, and

' Fig. 5 is a wiring diagram of a tandem propeller control system.

In Figures 1 and 4, I0 represents-an engine nose casing within which isdisposed an engine power shaft ll upon which are piloted concentricpropeller shafts l2 and I3, the shaft [3 being adapted to carry apropeller such as l4 in Fig. 5, and the shaft I 2 being adapted to carrya propeller such as IS in Fig. 5. The shaft I3 is piloted in bearingsiii in the engine nose, while propeller thrust from the shaft I2 istransmitted through a bearing I1 between parts of the shafts l2 and I3.

spider plate 24, the plate extending toward the shaft axes as at 25, tobe embraced by opposed similar members .26 each carrying a sun gear 21.

The members are secured to one another by.

bolts 23 and are provided centrally thereof with a bushing at 30, inbearing engagement with the outer surface of the shaft I2. Upon eachspider journal 23 is mounted a bevel pinion 32, the several pinionsbeing engaged on opposite sides thereof by bevel gears 3.4 and 35, theouter faces of which are borne by the members I! and 20. Each member 34and 35 is formed as at 31 and 38 respectively as an internal gear, theseinternal gears being opposite the sun gears 21. The shaft l3 carries aspur pinion spider 40 having pinions 4| engaged with the ring gear 31and the forward sun gear '21, while the shaft I2 is provided with a spurpinion spider 43 carrying spur pinions 44 engaged with the ring gear 38and the rear sun gear 21. The bevel ring gear member, 35-38, carries arearward splined extension 46 engaged by a correspondingly splineddriving plate'41 keyed to the power shaft II as at 43.

The drive sequences through the system are as follows: The bevel gear 35is directly driven by the engine through the drive plate 41 whereuponthe ring gear 38 rotates .the spider 43 in the same direction but atreduced speed, pinion reaction beingtaken through the sun gea 21. Thebevel gear 35 drives the pinions 32 which in turn drive the bevel gear34 at the same speed as the power gears 21 will be dissimilarwhereby'the sun gears will rotate Jointly to equate thehtorque loadingon respective driven shafts, which of course will .permit said shafts tooperate at difierent speed! but at similar torque.

Now. if the sun gears 21 b locked from rotation V by the use or lugs 50engaging in openings in the members 24 and 26, both shafts I2 and I3will be forced to rotate at the same speed-in opposite directionsregardless of any torque load differential.

I If the lugs 50 are arranged to permit of slight oscillation of the sungears 21 as by elongated slots in the member 24 as shown in Fig. 4, thelugs 50 will ride against one end of each of the slots 5| when one shaftis loaded more-heavily than the other, while the lugs 50 will rideagainst the opposite end of each of the slots 5| if theother shaft bemore heavilyloaded than the said one shaft. 7

The oscillation of the sun gears may accordingly be used as a controlmeans to govern the propellers for equal torsional loading, and, sincethe propellers are forced to rotate at the same speed, both propellers.will absorb the same power. The engine lubricating oil is used as amedium I j 80 to cause correction of propeller pitch to the point wherethe torque load between the two propellers is balancedwhereupon thesungear balanced and accordingly both propellers absorb for effectingpropeller control in the following manner: Pressure lubricating oilnormally passes inside of the power shaft II and this is conductedthrough drillings 54 and 55 in the shafts II and I2 to a plurality ofradial drillings 56 in the member 28. A plurality of radial drillings'51 are formed in the spider 24 to conduct lubricating oil to thebearings of the several pinions 32. However, one of these pinions isomitted as shown in Fig. 4, and is replaced with a pinion 59 journalledon a stub shaft Gilsecured to the casing III, said stub shaft having awormwheel 6| suitable for driving a centrifugal governor for onecontrollable pitch propeller, which governor would be mounted upon a pad82, the

governor itself being shown diagrammatically in Fig. 5 at B3. Theelement 24 adjacent theaxis of the shaft 60 is provided with paralleldrillings 65 and 66 which continue through the shaft 60 as drillings 61and 68 respectively; The web 26 of one of the sun gear units 21 isprovided with an offset groove 10 as shown in Fig. 3 which may registerwith lateral openings H or 12 of the drillings 65 and 86 respectively,according to the position of oscillation of the sun gear.

Thus, if the sun gear has oscillated against one extreme of itspermissible travel oil pressure will be opened to the drilling 65, whileif it has oscillated it to its other extreme of travel, oil pressurewill be imposed upon the drilling 66.

A control unit 14 comprises a cylinder communicating at its inner endwith the drilling 61 and at its outer end with the drilling 68. A piston11 slidable within the cylinder carries a switch arm 18 contaotable withswitch points 19 or 80 according tothe position of the sun gear. Theswitch points 19 and 80 are connected through slip rings, as shown inFig. 5, to an electric motor 82 which serves to eifect pitch changesprises the conventional constant speed apparatus where the propellerpitch is automatically controlled to maintain preset R. P. M. since thesun gears 21 do not permit any differential. However, if the rearpropeller offers more or less resistance to rotation than the forwardpropeller. oscillation of the sun gear 21 will close ing propellerswhether of the fixed or controllable pitch type. Many of the parts aresimilar, simplifying manufacture, such parts being I9-2II, 40-43, 21-21,pinions 32, pinions 4I-44, and except for an additional driving spline.the elements 34-35. Although the specific showing of the drawingrepresents a preferred and practical machine organization, it will beobvious to those skilled in the art that the proportions and detailedarrangements of the gears, Journals, and the bearings may be changed. Inthe reduction gear shown, the planet system would provide a reductionratio approaching two to one. If other gear ratios are desired, it isdeemed within the scope of the invention to change the form of reductiongears per se to attain such other ratios.

While I have described my invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding my invention, that various changes and modifications may.be made therein without'departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modifications and changes.I

I claim as my invention:

1. In gearing for oppositely rotating propellers concentric with a driveshaft, an internal gear on the drive shaft having bevel gear teeth, afixed bevel pinion spider with the pinions of which said bevel gearteeth engage, a sun gear connected to said spider, a first driven shafthaving spur pinions engaged between said internal gear and sun gear, asecond driven shaft having spur pinions engaging said sun gear, and asecond internal gear engaging the spur pinions of said second drivenshaft and having bevel ear teeth driven by said bevel pinions, said sungearbevel pinion spider connection comprising a floating bearingallowing relative rotation therebetween, and means responsive to saidrelative rotation to control the propeller load of one said drivenshaft.

2. In gearing for oppositely rotating propellers concentric with a driveshaft, an internal gear on the drive shaft having bevel gear teeth, afixed bevel pinion spider with the pinions of which said bevel gearteeth engage, a sun gear connected to said spider, a first driven shafthaving 'spur pinions engaged between said internal gear and sun gear, asecond driven shaft having spur pinions engaging said sun gear, and asecond internal gear engaging the spur pinions of said second drivenshaft and having bevel gear teeth driven by said bevel pinion, said sungear-bevel pinion spider connection comprising a joint having a bevelpinion spider with the pinions of which said bevel gear teeth engage, asun gear connected to said spider, a first driven shaft having spurpinions engaged between said internal gear and sun gear, a second drivenshaft having spur pinions engaging said sun gear, a second internal gearengaging the spur pinions of said second driven shaft and having bevelgear teeth driven by said bevel pinion, said sun gear-bevel pinionspider connection comprising a joint having a small degree of rotationalfreedom whereby the sun gear moves forwardly or reversely according tothe torque load on one or the other propeller, and means to control thepitch of at least one propeller to balance the torque load thereof withthe other propeller responsive to the forward or reverse movement ofsaid sun gear.

4. In gearing for oppositely rotating propellers concentric with a driveshaft, an internal gear,

on the drive shaft having bevel gear teeth, a fixed bevel pinion spiderwith the, pinions of which said bevel gear teeth engage, a sun gearconnected to said spider, a first driven shaft having spur pinionsengaged between said internal gear and sun gear, a second driven shafthaving spur pinions engaging said sun gear, a secvnd internal gearengaging the spur pinions of said second driven shaft and having bevelgear teeth driven by said bevel pinion, said sun gearbevel pinion spiderconnection comprising a Joint having, a small degree of rotationalfreedom whereby the sun gear moves forwardlyor reversely according tothe torque load on one or the other propeller, and means responsive toforward or reverse movement of said sun gear tobalance the torque loadbetween said driven shafts.

5. A driving system for tandem propellers comprising in combination anengine nose, a bevel pinion spider secured thereto at its outer ends,said spider including spaced gear bearings, bevel gears on each side ofthe spider meshed withthe pinions and carried by said bearings, eachsaid gear having internal spur teeth thereon, a sun gear assembly havinggear teeth opposite the internal teeth of respective. bevel gears, spurpinion spiders on each side of said sun gear assembly'having pinionsengaged with respective sets of sun and internal teeth, a drivingconnection to one of said beve1 gears, driven shafts connected torespective spur pinion spiders, means to secure the sun gear assembly tothe bevel pinion spider for limited oscillation, and means responsiveto'sun gear oscillation for adlusting the pitch of at least one of saidpropellers.

6. In tandem propeller drive means, axially spaced ring gears, means todrive the gears at equal and opposite speed, spiders rigid withrespective propellers having planets engaging said ring gears, and a sunmember having gear teeth engaged by all said planets, the sun gearbeingmounted for limited oscillation, and meansoperated by sun gearoscillation for controlling the pitch of one propeller. I

7. In a drive system for concentric propeller shafts, a power shaft,tandem internal gears one of which is directly driven from the powershaft, means to drive the other internal gear from the first gear atequal and opposite speed, a spider on one propeller shaft having planetpinions meshed with one internal gear, a second spider on the otherpropeller shaft-having planet.pin-

ions meshed with the other internal gear, a common reaction sun memberhaving gear teeth en'- gaged with the planets of both spiders subject toopposed torque reactions from the two spiders,

, and means responsive to differential torque reaction on the sun memberto control the driven load on one propeller shaft.

8. In a drive system for concentric propeller shafts, a power shaft,tandem drive gears one driven by and with the power shaft, means todrive the other gear oppositely at the same speed, a reduction gear fromeach said drive gear to one said propeller shaft, said propeller shafts,drive gears and power shaft being concentric, a normally stationaryreaction gear unit common to both reduction gears and subject totheopposed torques therefrom, and means responsive to unbalanced torqueon said unit torotate said unit a limited amount to control the drivenload 7 on one propeller shaft.

9. In a drive system for concentric propeller shafts, a spider havingradial arms and bevel pinions on the arms, bevel gears on opposite sidesof said spider engaging said pinions, means to drive one said bevelgearin one direction whereby the other bevel gear is rotated in oppositesense, the two propeller shafts being concentric with the gears andspider, a reductiongear'from each bevel gear to one said propellershaft. each reduction gear including a gear subject to reaction torque,means to secure said reaction gears to one another, and means responsiveto unbalanced torque on said reaction gears to change the driven load onone propeller shaft.-

' 10. In a drive system for concentric propeller shafts, a spider havingradial arms and bevel pinions on the arms, bevel gears on opposite sidesof said spider engaging said pinions, means to drive one said bevel gearin one direction whereby the other bevel gear is rotated in oppositesense, the two propeller shafts being concentric with thegears andspider, a reduction gear drive from each bevel gear to one saidpropeller shaft, said reduction gears including a common reaction membersubject to opposed torques from said propeller shafts, and meansresponsive to unbalanced torque on said reaction member to change thedriven load on one propeller shaft.

11. In a drive system for concentric propeller shafts, a spider havingradial arms and bevel pinions on the arms, bevel gears on opposite sidesof said spider engaging said pinions, means to drive one said bevel gearin one direction whereby the other bevel gear is rotated in oppositesense, the two propeller shafts being concentric with the gears andspider, reduction gear drives from said bevel gears to said propellershafts, said reduction gears including a common rotatably floatingnormally stationary reaction member, a driven load on each propellershaft, and means actuated by rotation of the reaction member to adjustthe driven load on at least one of said propeller shafts.

12. In a drive system for concentric propeller shafts, a drive member, apair of planetary reduction gears driven by said drive member and eachdriving one said propeller shaft, the reduction gearsaifording oppositedirections of propeller shaft drive. said reduction gears ineludingplanet elements and sun elements. one of said elements of each reductiongear comprising a reaction member, said reaction members being securedto one another and being subject to opposed reaction torques from thetwo oppositely rotating propeller shafts, and means responsive todiflerential torque reaction on said members to alter the driven loadonone propeller shaft. WILTON G. LUNDQUIST.

REFERENCES CITED The following references areof record in the illeofthis patent:

Number UNITED s'ra'ms parnu'rs Name Date Menasco Nov.-2, 1939 EganV,Jan. 2, 1940 Buck Apr. 18, 1939 Wlllgoos Aug.8, 1939 Martin July 5,1938 Gosslau et a1. Jan. 16, 1940 Wiegand Aug. 14, 1934 Kenney Sept. 24.1940 Walker Apr. 12, 1921 Palmer Mar. 26, 1940 Blanchard Sept.'6, 1938

